Heretofore, imino[(substituted or unsubstituted phenyl)amino]acetic acids have been known from such references as Japanese Patent L-O-P Publns. Nos. 589/1963, 14041/1963 and 20197/1964, Japanese Patent Publns. Nos. 10287/1975 and 22018/1975, Japanese Patent L-O-P Publns. Nos. 108933/1978, 88158/1982, 85351/1982, 85352/1982 and 38249/1983, and J. Org. Chem., 43, 4485-4487(1978), but these references fail to disclose imino[(3-fluorophenyl)amino]acetic acid. Further, Japanese Patent L-O-P Publn. No. 88157/1982 discloses imino[(substituted or unsubstituted phenyl)amino]acetic acid esters as reaction intermediates, but it fails to define structures of the esters as isolated and also fails to refer, in concrete, to imino[(3-fluorophenyl)amino]acetic acid derivatives or imino[(3-chloro-2-methylphenyl)amino]acetic acid derivatives. Further, some of the above-mentioned prior art references suggest a possibility that imino[(substituted or unsubstituted phenyl)amino]acetic acids have general herbicidal activities or agricultural activities, but they fail to describe concretely these activities of the acids and hence it can hardly be said that said acids are disclosed as herbicides.
In this connection, any compounds which are considered to be useful as herbicides, particularly those for use in a paddy field, are required to have the following properties.
(i) The compounds have no phytotoxicity to paddy rice, PA0 (ii) said compounds exhibit herbicidal activities to weeds, in particular, water chestnut (Eleocharis kuroguwai) and water nutsedge (Cyperus serotinus). PA0 (iii) said compounds exhibit herbicidal activities even in the treatment of barnyardgrass of the 3-leaf stage.
After extensive researches conducted with the view of obtaining compounds having such properties as mentioned above, we have accomplished the present invention on the basis of our finding that imino[(3-fluorophenyl)amino]acetic acid derivatives, which compounds are novel have excellent herbicidal activities. The invention thus accomplished has been based also on our further finding that imino[(3-chloro-2-methylphenyl)amino]acetic acid derivatives have excellent herbicidal activities.